Experiment 9: Determination of Dissolved Oxygen Flashcards
The acceptable range for environment of this parameter:
pH
6-9
The acceptable range for environment of this parameter:
TSS
Less than 150 ppm
The acceptable range for environment of this parameter:
TDS
Less than 2100 ppm
The acceptable range for environment of this parameter:
DO
4.5-8
The acceptable range for environment of this parameter:
COD
Less than 200 ppm
The acceptable range for environment of this parameter:
BOD
Less than 50 ppm
- refers to the level of free, non – compound oxygen (O2) present in water or other liquids
- oxygen that is bonded in water is a compound oxygen
- high level or low level of DO affects the aquatic life
Dissolved Oxygen
Dissolved oxygen is used for respiration for aquatic life like:
fish,
invertebrates,
bacteria and
Plants
bottom feeders, crabs, oysters and worms need minimal amounts of oxygen
(1-6 mg/L)
while shallow water fish need higher levels
(4-15 mg/L)⁵
Where does DO come from
- photosynthesis
- diffusion from atmosphere
- wind cycling
- 100% air saturation:, equilibrium will occur:
- Photosynthesis occur
- the water will slowly absorb oxygen and other gasses from the atmosphere until it reaches equilibrium at complete saturation.
- use of wind-driven waves and other sources of aeration can speed up the absorption of oxygen.
Upper water
- DO is below 100% due to the respiration of aquatic organisms and microbial decomposition.
- are not shallow enough to be affected by the waves or aeration and photosynthesis at the surface.
- is below an invisible boundary called the thermocline (the depth at which water temperature begins to decline)¹¹.
Deeper water
factors that affects DO
- temperature
- salinity
- pressure
relationship of DO with temperature and salinity
DO decreases as the temperature and
salinity increases
